Grinding machine with crush wheel dressing mechanism



P. A. GROBEY Sept. 21, 1954 GRINDING momma mm CRUSH WHEEL nmassxuc MECHANISM Filed Oct. 5. 1951 5 SheetsSheet l P 21, 1954 P. A. GROBEY 2,689,434

GRINDING MACHINE WITH CRUSH WHEEL DRESSING MECHANISM Filed Oct. 5. 1951 5 Sheets-Sheet 2 p 21, 1954 P. A. GROBEY 2,689,434

GRINDING MACHINE WITH CRUSH WHEEL DRESSING MECHANISM Filed Oct. 5. 1951 5 Sheets-Sheet 3 Sept. 21, 1954 Filed Oct. 5. 1951 P. A. GROBEY GRINDING MACHINE WITH CRUSH WHEEL DRESSING MECHANISM Jaw/2Z l3 f/Wi [ZZZ P 1954 P. A. GROBEY 2,689,434

GRINDING MACHINE WITH CRUSH WHEEL DRESSING MECHANISM Filed Oct. 5. 1951 5 Sheets-Sheet 5 Patented Sept. 21, 1954 UNI smrssi; PATENT" OFFICE;

GRINDING MACHINE WITH CRUSH WHEEL DRESSING MECHANISM PauleiAxi Grobey; Springfield; i: Vt .,i assignori ito Bryant Chucking Grinder; Company, Springfield vt a corporation ofhVermont. 7 Application October 5, 1951, SrialNo.-249,88ll

10- Claims. 5 (Cl. -51--5) This invention relates to grindingcmachinesw and: while not restricted-thereto, is particularly applicable to machines stwhereim 'r'the i'grindin gu wheel has a contour of a shapexdiflicultfto dress by means oflza single?dresslngspoint or" diamond, so" 1 that crush dressing; xparticularly radvan tageous.

One of the objects ofsthe invention is:topro z vide dressing mechanism, more parti'cularlywof: the crushing type, witlimeans ioriautomatical lyi presenting it to the wheeliandir'emoving it there r. from after a predetermined humbere':of? grinding r operations have been :completed'x: it

Still another object oi thednvention -isito pro-- vide for feedbf a pair .of crushingt rolls from diametrically opposite'i sides l against "the -wheel thereby to relieve the grinding wheel mounting from unbalanced -spressurer-rdue to the: dressing operation.

Still another object: is to provide =for relative 20 feed between the-work holder and tlie grindingwheel to compensate: for wheel siz: reduction due to wearand dressing.

Still another objeet is to' provide' a wheel drive for'dressingi slower than normalgrin'rliiig speed For 'a more complete understanding oil-this '1 a vention reference 'maywbe :hadto the aocompanying drawings in' whichw.

Figure 1 is "a fragmentary top-plan viewbfan internal grinding machine embodying the in'vem' i tion, the dressing mechanism beingshown fiini dressing position;

Figure 2 isa fragmentary front elevation ofl the same, the dressingmmechanisni being show-n retracted."

Figure 3 is-a sectionalviewmn line"-3- 3-'bf Figure l. V

Figure 4 is a fragmentaryrearelevation of the machine, partsbeing broknawav? Figures 5 and 6 are detail sectional views on lines 5-5 and: B--6,"respectively} oftFigurei3."

Figures 7,"3 and 9 are detail sectional views on the correspondingly"numbered section lines of Figure 1.

Figure lOisa detailsectiohal .view toia larger scale: on line Ill-J0 of .Figure- 2.,

Figure 11 is a view similar to; Figureifl but showingwthe parts indifferent relative positions andwitheertainaclditional partsia. 5

Figurelz is a detail.isectinnalrzwiewi:on-:linew I2-'I2 of Figure 2.1,.

Figure 13: istarrdetail sectionalivie'w son linear Iii- 43: ofiwFigure" 12.5 t

a weight. :I B: connected'through a "cable?! slow speed azcru'sh dress driving mechanismax clutchedrwthereto. V

Figures 16 and- 17 are detail sectional= VieWsYI-r to' a larger-scaleon lines-16 and l1-l1, respectively; of Figure-15.

10 Figure 18 is an elemental wiring diagramxfor:

thermachine. 1

Referring? first to Figures -1 and"2,'the grinding machine as shown comprises 1 a rbase I which: supports' wheel head Zprovided with a grinding: wheel "shaft '3 carrying ;the--grinding:::wheelMA This shaft3 maybe integral with the armature shaft of a high speed motor, the-casing for which is shown atlai (Figure15); Also -mounted om the beds! is a twork head 5 lhavingl journaledw thereina suitable work :spindle provided with a workiholderfi at one: end, and a beltipulley- 1 at the-other, over which passes a drive belt-8 leadingitosanysuitable driving motoraSM- (Figure 18 bywhich the work spindlemay be rota-tedr-soas? r to :present rotatingz work to the grinding wheel 3. The work head is movable-on thebedl transverse itowthe -direction-of .th'e'wheel "spindle i3, and it is-so-movedto producer-relative feedbe-r tween -thel-vgrindingwwheel 4 and worle-car-riedm ,by:-the-workspindle as=iswell lmownin'the art;

Thewwork head 5 isprovided with dependingw bearings'oneeof-whieh is.shown-at -I0 -in-Fig-p ure 12iand which are mounted on ways provided 7- with. dust-excluding bellows l I: and wl 2g-=as shown --1 in this i-figure, awhichr surround: the ways andseal r" them" to thev-dependingiz-portions: I 0.- of the work heart: A The 1 work head; 1 is :provided with a .Lwall: member I5 carryingyanzabutment -.I6 whichuis pressed. against :therendi of.-a feed shaft' I1, asdoy 9' to the head-5 andpassinggoverca pulley'zla As ishown in Figure l3; th'evshaftrl l is; threaded"? as.:at2 5: within an internally'thread'ed 'nut 2 6: tot:- whi'ch is keyed a feed leveroz'l: By: ro'cking' this :1 a

feed" lever itii's evidentuth'atithe' shaft? l 1; may be'l m-ovedraxiaily without -1being;::rotated. This "provid'es ZfOI'l tilET normal feed of l the? work head; with: a respectto'athegrinding wheelgbutia further feed is provided to c ompensatetfor wheel 'wearsanditruingm o whichrreduce the3sizezof thetwheLxThis is pro-fr feed mechanism at M having a dog 32 which engages a ratchet wheel 33 (see Figure 10) secured to the shaft 30. This ratchet mechanism is actuated by the rocking of a bell crank lever 34 fuicrumed on the shaft 30, one arm of which is connected through a link 35 to a T-shaped lever 36 fulcrumed at 31 to a fixed portion of the machine. A second arm 38 of this lever is connected through an adjustable link 39 to a flexible pull cable ii) which may be actuated by means which will later be described.

In normal grinding operations, the grinding wheel 3 is driven at high speed through the high speed driving motor of which the shaft 3 forms a portion of the armature. However, at certain times it may be desired to dress the grinding wheel, and particularly where this grinding wheel is of somewhat intricate shape which it is difficult to produce by the motion of a single truing point, it may be desired to effect the truing by a crushing operation. In order to effectively crush dress such a wheel it is necessary to reduce its rotating speed very greatly. For this purpose there is provided a slow speed driving motor IM, which, as shown, is mounted on the casing 2a of the wheel head which houses the high speed grinding wheel motor.

The driving connections from the slow speed motor IM to the wheel shaft 3 are illustrated best in Figures 15 to 17. As shown in Figure 15, the drive shaft 50 of the low speed motor IM is provided with a pulley about which passes a belt 52 which also engages about a pulley 53 secured to a hollow shaft 54. This hollow shaft 54 is journaled in spaced bearings 55 and 55 in a bearing box 51 shown as formed integral with a stationary end wall 58 for the wheel housing 2a. Within this housing the shaft 54 is provided with a spider 60 within the outer portion of which are pivoted, as on pins BI, a plurality of friction clutch shoes 62, four such shoes being shown in Figures 16 and 17, arranged syrnmetrically about the axis of the hollow shaft 54. The inner ends of these shoes I52 are pressed inwardly radially as by springs 63 seated in a socket 64 in the shoes and engaging the inner face of a ring 65 which surrounds the shoes 52. The innerends of the shoes 02 are provided with. friction pads 06 which may engage the periphery of clutch pulley 61 which is secured to the rear end of the wheel shaft 3. This arrangement provides a frictional drive for the shaft 3 from the hollow shaft 54 which is driven by the motor IM at the slow speed, this slow speed drive being accomplished when the high speed motor portion of the wheel'drive is deenergized and the shoes 62 are in driving engagement through the friction means with the shaft 3.

Means are provided for withdrawing the shoes 62 from such frictional engagement to permit the wheel drive to be produced by the high speed drive. This is accomplished by pressing to the left, as shown in Figure 15, a rod 10 which passes axially through the hollow shaft 54 and at its inner end is provided with a tapered portion II which engages a series of balls 12 and presses each of these balls outwardly, forcing outwardly radially arranged pins I3, the outer ends of which may engage the shoes -62 somewhat inwardly of their pivots 6| and force them outwardly against the pressure of the springs 03. This operatively disconnects the slow speed drive for the grinding wheel. This axial position of the bar It is controlled by the angular position of a T-shaped lever 15 fulcrumed at 76 on a bracket I1 secured to the stationary wall member 50. One arm 39 of this lever 75 is provided with an adjustable stop which may engage a boss BI on the bracket ll to limit the pivotal motion of the lever in in one direction. A second arm 82 of this lever "I5 bears against the outer end of the bar I0, and a finger 03 attachedthereto as by a screw 84, is provided with a portion which engages the left hand side of a head 85 on the bar I0. Thus as the lever Iii is rocked, the bar i0 is moved positively in either direction. A third arm 31 of the lever i=5 has connected thereto one end of a cable 88 which passes axially through a cable cover 83 held in a clamp 90 carried by a bracket 9! secured to the bracket TI. Axial motion of the cable 88, it will be clear, will serve to rock the lever '55 and thus control the axial position of the bar 70. By this means the operative connection and disconnection of the slow speed drive motor M to the wheel spindle 3 is effected.

The wheel dressing mechanism is carried by and is thus movable with the work head, but it is pivotally secured thereto as on the pivot shaft I00. It comprises a supporting frame member IOI to which the pivot I00 is secured and which carries slidably a pair of parallel spaced bars I02. The outer ends of these bars I02 have secured thereto a head I03. As shown in Figure 5, this head I03 has secured therethrough a bearing member I03 which has journaled therein a shaft I05. This shaft I05 is provided with a shoulder I00 which is drawn against the inner raceway of one of the ball bearings IGI of the bearing member as by a nut I08 threaded on its reduced diameter end portion and bearing against the inner raceway of a second similar ball bearing I09. A cover plate III) bridges over the nut I08 and one end of the bearing member I04, and screws I I I, secure the cover plate and the bearing member I04 in position. The opposite end of the shaft I05 is provided with a head i 55 over which may be engaged a crush dressing wheel I It; having its periphery shaped complemental to the desired configuration of the grinding wheel 4. This crush dressing wheel may be removably secured to the head II5 as by a headed plug I20 and is free to be rotated by the rotation of the grinding wheel when it is brought into contact therewith. By a similar mounting a crush dressing wheel I2! is supported on a slide E22 having a shank I23 longitudinally slidable on the frame member IBI. This shank I23, as shown best in Figure 6, is of trapezoidal cross section and may be clamped rigidly in its slideway by the removable guide member I27 which is secured in position by screws I24.

The bars I02 are slidable through the slide I22 and their ends opposite to the head I33 are secured in a frame member I25. This frame member carries an adjustable stop screw I25 which limits the approach between the frame I25 and the head I22, these parts being pressed together as far as permitted by the stop I26 by coil springs I28 having their ends secured in eyebolts I20 in these parts. These springs therefore tend to separate the two crush dressing wheels H6 and I2I as far as is permitted by the stop I26 at such a distance that they may straddle the grinding wheel i at substantially diametrically opposite sides when this mechanism is in the full line position shown in Figure 3. As the frame IOI is pivotally supported, it may be rocked to the dotted line position shown in.Figure 3 with the crush dressing wheels H6 athe sts and; IM outgofjilcontact withzthes grindinmwheel 4;; and this t is: the; normal t-positiom of 1 the: parts during thel grinding operation. -I*Io.w,e.ver; when crush-I dressinglis to; toe effectedfi; the -.cr ush dress in imechanism is, brought to its full Ilinewposition-shown in-Flisure 3, and the crushndressing wheels are pressed. heavilyr-againsti opposite-sides of'Ithe grinding wheel to effect. the: dressing: operation, these dressing :wheelsheing freeIto revolve withthe: grinding wheel;

"The: rocking of the; crush dressing wheels-into dressing -position causesraz camrmember I car,- riedbyithe frame-I I25 by: pivots-.13.: and I32, thelatter being, mounted: in.- a, slot I33,-=in*,the frame and. adjustable-therein;by theadiustment screw I34, to IrideI-intoIcontact with-,a follower, roll I carried ,by, a;lever I 3.6, pivoted-at: I 3;! I on -a bracket I,16,-,secured: toIa :bracket member, IAiLfixedto :the machineh-bedzl. The lower endofthe lever I35 isxconnected through a I link I45, adjustable in length, to a bracket I dfivsdependingfrom the work headIS. Riding of the oammember Its along the follower: I35movesthe. frame I25 to the right, as viewed in-Ei ureI 3,. pulling the crush dressing, wheel I I 6, toward the axis ,of, the-grinding-wheel I. Motion of,:the work, head-tolthe left, as viewed in Figure 3, thus acts, to'press theI-followenroll; I35 against, the cam I35 and pullthe rods I02 in ,a direction to move the crush dressing roll wheel H6 toward? the: axis of, the, wheel 4, and the motion-of. the, wort:v head inethis direction, carryingiwith. it the: pivot we tot-which. the slide I22.1-is secured. by the grip fit of;.its.shank.II 23 :in the. guideway, I IJIIlas previously described, movesathe crushing I wheel I 21, in the oppositedirection Iandagainstlthe grinding wheel, thus squeezingthe grindingxwheel .4, between them with.,an equalized pressure. This. lever; and. link mechanismueffects the compensating feed for w-heelwear andutruing, the two :arms. of .the lever I 3IB-lbeing of equalaefiective -lengths.

The variousIoperationsIof the. machineareactuated byaI-series of electricmotors. Themotor IM which [I drives I, the-I grinding, wheelI shaft 3.;atethe low. speed, andthe, high frequency, hi h speed drive, forthis shaft?havepreviously; been described. I ,Thevarious, usual steps, of the grinding cycle,v such as relative approach and retraction betweenihe grinding I wheeland theIwork, are

actuated by, a.motor:;4l ashownIinithe. diagram of Eigure 18 .and which ;drives a mainzcamshaft I: shownin Figure I 141 having ca'ms for; accomplishmg thIese, functions, and as these ;are;old and'well known, no, specific; showingof them-I is? containedherein; ifhis cam shaft. is; also provided with a cam: I5 I which acts at one; angular. positionjof the camshaft tomomentarily actuate azsw-itch LS8, after, which thisswitchreturns to its formerposithan. I It; also I carries, a. cam I 52:- which at certain times may close a normally openswitch LS6. This switch I LS6, Iaswill later, appear, is inthe control circuit. for; a: feed; i'notor BM shownboth in the diagram-I of FigurelB and in Figure 14. This motor GM; is, connectedby: the :belt I53I-t0 aishaft;

lMIconnec-tedthrough alworm-geap drive-with ashaftII 55. This shaft I55 carriesa cam l-56wwhich cooperates ,with Ia follower, I58} This-I lever I53 is fulcrumedtat I5IBIandits oppositeendis connected through alinh :II BIO-to the; arm 27 of l the feed mechanism shownbest 1 in Figures 2,.and13. so thattas the cam; I55 isI-ro-' tatedit. lifts the arm 21 and producesua; feed actuationof the feedshaft I1; This-shaft I55 5.1304 carries; cams; which: at suitable r. times! :closethe normally open switches-LS .andILSfhI IT-hep I51. carried-Iby -a-Ilever amangementc-byrwhich; certain ofithemmachine contnolsare; effected byscamsscn amain camshaft and the. feediis; effected by a second feedcam shaft, the: tWOTLCfiIU-l shafts; being I: rotated-.-alter. natelywhilathe otherjs stationary isnotclaimed herein, but; forms subject; matter-of my application: Serial? No. 236,297, filed J uly- 12,, 195.1, for; AutomaticGrinding':Machine.

The-.motionof; the dressing wheel mechanism from; the :dressing: position shown in: full linesiin Figure.- 3; to. the. idlepositionshownin ldottedlines is: produced by-a:;cam I70 carried by a dressing camshaft; If! I I l'IhisII'cam'shaft-I I 1 I ,iarotatedlby a motor; 3Mshownrin Figural; anddiagrammaticab ly.:.ini.Eigure 1.8. The shaft I12: of thismotor-is, connected through-.arbelt :drive'at I l3ywith:a;shaft I14 of a suitable reducing gear mechanism (not shown) Within a case I15,;to'the shaft; I'I.I., vThe cam; I'll}; actsluponaIfol-lower roIll I60 (seeliigure 7)- which is carriedyby an arm IBII'fiXed tothe shaft .IDB, to; which isIalsd fixed the truing mechanism as:,previouslydescribed. This arm I 8 I .has; astop: member; I82, which, cooperates. withan ad: justablezstop screw I83; and whenithe partszare. in--thisI position; as shown in Figure I, thetruing mechanism isin its'operative full line position: shown inufiigure 3. The, cam- I'Iil: has ,a lobe I84, however, which on rotation of the shaft lll in the direction of the arrow shown inFigur 'l and to the position shown. inFigure 11, maycQntact and depress the follower roll I IBEI andzswing the truing mechanism up into the inoperative dotted line position shown in Figure 3 and in Figure 11. This cam Illi also carries a cam projec-- tion I85 whichlifts a follower roll; I88 of 3,1110!- mally closed switch LSI I to hold this switch open when the: dressing mechanismiis in retracted'position.

The camshaft I'll also carriesa secondcam disk I98" (see. Figure 8) with which cooperates: a follower roll IQIIonaleVer I92fulcrumed at I 93ona stationarybracket I94; 'Th-isfollowerl 9I;is held: in, contact with the cam; dish, lfifigasby, a spring I95, and to; its upper, end is, connected; through a link I96 a flexible cable iiiwhich is ,slidable through a cablecover; l lil-heldby a; bracket I99. This cable MLIwhichIasIpreviously described, extends to thefeed compensatinggmechaniszn by which the feed betweenthewrzork head; and the wheel head is, actuated a predetermined amount wheneverjdressing is beiing effected. As-shown this. mechanism is givenfour actuations during,

each driving operation. This-cam shaft. I'll also: carries a thirdcam 285); (see, Figures 9 and 11) which has a cam lobe 2G I which at theendofthe. crushingengages-a followen292 carried by alever 293; fulcrumed. at, 28 onthe; bracket I99. The follower 262 is normally-held toward: thecam 200" as by a spring 295 and itsouterxendisconnected through an adjustable link; 258' to: the. flexible cable: 88 whichis slidably housed within the cover 89. As previously: pointed; out, pulling of this cable with the parts in; the; position of Figure 11 pushes the, rod, 79 :releasing the I low speed; drive and allows the: highspeed drive: to Ibecome effective on the; grinding Wheel 4.. Themam shaft I'H' stops in the position of the parts shown inEigure 11.

Referring to the; diagram: in: Figure lt8lshowing the parts I in. idleI- position, the high. frequency high speedrmotorf 2M) which drives the grinding wheel during-the; grinding portion of the "cycle is driven from a suitablehigh frequencysource, comprising the highzlfrequency ,1ineS1 259,' 25'l I 252, through a main switch 253. -Whenf-thismain switch 253 is closed, the motor 2M is controlled by other mechanism shown in the lower portion of this figure, energized by a low frequencylow voltage control circuit derived from the secondary 255 of a transformer 258, the pri-- mary 251 of which receives its power from the normal frequency lines 250, 261, 252 through the main switch 264. The motors 1M, 3M, 3M, M and 5M all derive their power from the lines 260, 261 and 232. The crusher cam motor 3M and the crusher slow speed motor 1M are controlled simultaneously by the same mechanism, so that when the crusher cam allows the crushing mechanism to swing into operative position, the slow speed drive for the wheel is started, the fast speed drive for this motor having been disconnected.

The operation may be understood from an inspection of Figure 18. Closing of the master start switch 210 establishes a circuit from a transformer secondary 255 through leads 211 and 259,

switch 210, lead 212, closed stop switch 331, leads.

338 and 339, control switch 1m and lead 348 to lead 211 back to the transformer secondary. Closing of the control switch 1m closes a holding .switch 239 which is shunted around the master switch 210. The control switch 1m when closed may also start into operation various auxiliary apparatus (not shown) such as lubrication and coolant circulation apparatus, as is well known. Closing of the master start switch also starts the high speed grinding wheel motor 2M as it closes a circuit from lead 213 through lead 213 and closed C switch 336, CR3 switch 355, CR2 switch 355 and the control mechanism 2m for the motor 2M.

switch 285, lead 281, control 4m, lead 288 to the lead 211. The control 4m then starts the main cam motor 4M shown in the upper portion of Figure 18. Also a holding 4m switch 283 shunted about the switch 285 is closed so that the main cam motor 4M continues in operation even after the switch 235 is allowed to open. Each rotation of the main cam shaft [50 momentarily moves a swith LS8 from its upper to its lower position shown in Figure 18, establishing a circuit from lead 233 through lead 209, switch LS8, lead 388,. counting mechanism CNTR and lead 381 to the lead 211. Until the predetermined number of actuations of the counter corresponding to the desired number of grinding cycles between truings of the grinding wheel have been had nothing results from this actuation of the switch LS8 except to deenergize the relay CR! which, as will later appear, is energized at the time the switch LS8 is so moved.

The rotation of the main cam shaft H53 acts by suitable cam mechanism driven thereby to advance the wheel into operative relation to the work, whereupon it closes the switch LS4 and immediately thereafter closes the switch LS5. Closing of the switch LS4 closes a circuit from the lead 281 through the lead 283, the switch LS4, lead 282, motor control 5m and lead 283 to the lead 211. This starts rotation of the work spindle by energizing the work rotating motor L5M. Energizing the relay CR2 opens the CR2 switch 3H5, opening the clutch connection between the cam motor 4M and the cam shaft 158 and closes the CR2 switch 311 and applies the brake, stopping the rotation of the main cam Shaft.

Energizing the relay CR2 closes the CR2 switch 310 which closes a circuit from lead 298 through lead 3| I, closed switch 310, closed CR4 switch 312, lead 313, feed motor control 8m and lead 314 to the lead 211. This closes the feed brake switch 315 to release this brake so that the feed motor 8M turns the feed cam shaft 155.

The rotation of the feed cam shaft I55 first acts to close the switch LS1, which maintains the CR2 relay closed, by establishing a circuit around the open switch LS6 from the lead 298 through lead 323, switch LS1, and lead 325 to lead 308. Toward the end of a complete rotation of the cam shaft 155 it momentarily closes the switch LSI2 and thereafter permits the switch LS1 to open.

The momentary closing of the switch LSl2 closes a circuit from the lead 298 through the lead 320, switch LSI2, leads SH and 322, relay CRI, and lead 323 to lead 211. Closing of the relay CR1 closes its holding CRi switch 324, which with the switch LS8 in its upper position maintains the relay CRI energized. Opening of the switch LS1 then with the CR! switch 301 open through the energization of the relay CR1 deenergizes the relay CR2. Change thereafter of the switch LS8 to its lower position deenergizes the relay CRI.

Deenergizing this relay CR2, then actuates the switch 311 to release the brake and the switch 315 to close the clutch, re-starting the main cam shaft I58 and the rotation of this main cam shaft continues for another portion of the cycle. This action continues, alternately rotating the main cam shaft and the feed cam shaft until the number of complete grinding cycles for which the counter C has been set has been reached. When this has been reached, the actuation of the switch LS8 to its lower position, as shown in Figure 18, causes the counter to open the counter switch 336 in the circuit to the high frequency grinding wheel motor 2M, so that this motor stops. The C switch 335 is closed and this establishes a circuit from the lead 212 through the closed stop switch 331, leads 338 and 338, lead 339, C switch 335, lead 340, the crusher cam starting mechanism 3m and lead 341 to lead 211. It also closes the circuit through the brake 3%, which is a spring-closed electricallyreleased brake, for the cam shaft motor 3M so that the crusher cam motor 3M starts. Energizing of the control 3m closes the 3m switch at 350 which with the closed C switch 335 establishes a holding circuit from lead 213, through lead 35!, 3m switch 350, and lead 339, C switch 335 to lead 380. The closing of the C switch 335 also energizes the relay CR4. This opens the CR4 switch 383 in the control circuit for the motor control 2m and it also closes a CR4 switch 361 which by-passes the switches LS6 and LS1 and closes the relay CR2. Closing of this relay CR2, as before noted, stops the rotation of the main cam shaft, opening the CR4 switch 312 in the feed motor circuit 8m so that the motor 6M cannot operate during the dressing operation. The crusher wheel motor IM being controlled with the crusher cam motor 3M also operates when the crusher cam motor 3M starts to rotate. The rotation of the crush cam motor 3M from its idle position of Figure 11 causes the cam lobe I84 to release the follower I80, allowing the crush dressing mechanism to drop to the full line operative position of Figure 3 and the cam lobe 201 releases the follower 202 to the position shown in Figure 9. This latter action allows the cable 88 to be moved by the spring 205 in 9. direction to wlthdrawsthe: rodlu into the position Shown. Fig rewliwherein the; slow speed wheel drive from the motorqlMis eifective toydrive thegrindingv wheel at-slow crushing speed;

Continued rotation of the i dressing, cam shaft 1H causes thecam lstband the spring I95 to alternatelypush and pull on the cable 40 to step around-the feed ratchet whee1-33 (see Fig: ure and feed the crush dressing wheels againstnthegrindingwheel. This dressing actiontakes place until the dressing; cam shaft Ill has completed one revolution andisinthe position of Figure; 11 wherethe cam lobe I84 acting on the follower-illfl has returned the dressing mechanism to itszi-noperative dottedv line 'pos-i+ tion of Figure-3; the follower 202has-been lifted, pulling thezcabIe-BEm-and opening the friction drive connection between the motor i l M andthe grinding wheel by projecting the rod 70 between the rods 13, .andrtliie stop-switch LSI I has;

been closed by the'cam-element I85 as shownin Figure 11.

Closing of thesw-itch LSII- establishesa cirouit from the lead 213 through switchLSl l lead 360, relay CR3 andlead 36l to the lead 211. The circuit is also completed from the lead 360 throughthe lead 362 and counter re-set device 363tothe lead 211 which sets the counter C back to starting position for anew series of grinding cycles before the truingq mechanism will again be operated.

Closing of the relay-CR3 closes therelay CR3 switch at-365 whichstarts the high frequency grinding wheel motorsZM. vIt also opens the CR3,

switchattfil which deenergizes the relayCR4,

stops the crusher cammotor 13Mv and the crusher wheel motor: -I M, and-allows the brake 344, to .stop the crusher cam motor. The; parts; are then in position for repetition of the grinding cycle.

From the, foregoing descriptionxlof :anv embodiment of this'invention it.=should be evident to those 1 skilledv in, the art that various changes and modifications may xbe made; without depart.- ing' from its spiritor, scope.

I claim:

INA grinding machine having .a. grinding wheel, means. selectively operatively =l connectible thereto for rotating said wheel at a higher grinding speed 3 or at 1a. lowers crushing speed, a wheel crushing mechanism comprising a pair of spaced freely rotatable crushing wheels between which said'grindingwheel'may be engaged, a'support carrying said crushing wheels, meansrmounting said support for motion from and to a position whereinisaid crushing wheels arepositioned on substantially. diametrically opposite sides of said grinding wheel, means .operatively connected thereto for. moving said supportfrom and to said position and for moving said'crushing wheels toward and from each other to crush dress and then retractirom said grinding wheelwhen said support is insaid position, a cyclecounter operatively connected to said grinding machine to be actuated by one count by each grinding cycle of the machine, and means operatively connected to and actuated by said counter at the completion of a predetermined :number of ,grinding cycles toactuate saidisupport-moving means" to position said crushing wheels in said position and to move said crushing wheels toward each other to crush dress said grinding wheel and thereafter to retract said crushing wheels and remove said support from said position.

2. A grinding machine having a grinding wheel, means operatively connectible thereto for rotating csaid iwheel at: high grindin sp me n operatively:connectibleithereto for rotating said wheel at :a slowencnushing speed, awork holder,

means for ieedingrsaidv holderand wheel rela tively, a wheel crushing mechanismmovable be:- tween an operativeand inoperative position with respect tosaid grinding Wheel; ope a-.

tively.connectedatheretoior acting automatically, after; a predetermined number; of, grinding cycles to render saidhx haspeed rotating: means inoperative and said; slowspeed'rotating means op tive to drive usaidegrinding Wheel, and to move said mechanismfirom:.hioperative to operative position to: crush i dress said wheel, said wheel, crushing mechanisin oornprisinga pair of spaced freely rotatable crush sdressing wheels between.

wear and dressingin. the :relative. positions ,be-

tween said work I holder and. grinding wheel.

3. A grinding machine having a rotary. grindingwwheel, means. for. rotating said wheel, wheel; crushing mechanism: mounted for swinging 1110-; tion from and towardiseidvgrinding wheel, said mechanism comprising :a pivotally mounted. frame, a pair of: hard crushing wheels 1 mounted for free rotationlinsaidrframeandior relative motion from and toward; each other, said lcrusha 1 ing wheels beingndisposedz relative to the pivotal: mounting of said frame. anclsaid grinding wheel: to be positionedron..diametrically opposite sides.

of aid grinding wheel. when i said mechanism is swung towardsaid g-rinding wheel, and cam means operativel-y; related to said crushing,

wheels and -actuawtedhy themotionof said mechanism toward "said; grinding wheel to move said crushing wheels .in-to contactwith said grinding Wheel.

4. In ,a grinding .rna-chine having a rotary,

grinding wheel and means for rotating said Wheel, 3493-1151511 dressing mechanism pivotally mounted. on said ,mach-inefor swinging between, an operative: and 3 an inoperative position, and

having a pair-voimovablywmounted freely rotatable crushing: wheels rsllpnorted for crushing .en-

gagement. withsaidg-ghind n .wheel and i for rota-. tion thereby when said; mechanism is in said; operative position, means-operatively connected;

to said rnechanism actuable toimove said mechanismf-rom said-inoperativeuto said operative position, and means operatively connected to said crushing wheels andeffectiyetovmove said crushingwheels into pressing contact with said grinding wheel by the movement of--said mechanism into operative. position,

5. In a grinding machine having a rotary grinding ,wheel sand-means for rotating said Wheel, a crush dressing :mechanism pivotally mounted on saidrmachineqfon swinging between an operativeandwan inoperative position, i and avin -a p r of morablymou t d;fr e r at able: crushing wheels supported-for;crushing en gagement with said grinding wheel and for rotation thereby when said mechanism is in said operative position, means operatively connected to said mechanism actuable to move said mechanism from said inoperative to said operative position, and means operatively connected to said crushing wheels and effective to move said crushing wheels into pressing contact with said grinding wheel by the movement of said mechanism into Operative position and releasing said pressure-by motion of said mechanism away fromv operative position.

6 A grinding machine having a rotary grinding wheel, grinding wheel crusher mechanism comprising a frame, a pair of crushing wheels carried by said frame and movable from and toward the axis of said grinding wheel, and cam means operatively connected to said crushing wheels and including a cam having a plurality of active portions constructed and arranged to move and press said crushing wheels against said grinding wheel intermittently a plurality of times during each crushing action by continuous motion of said cam means.

7. In a grinding machine having a rotary grinding wheel and means for rotating said wheel, a crush dressing mechanism pivotally mounted on said machine for swinging between an operative and an inoperative position, and having a pair of movably mounted freely rotatable crushing wheels supported for crushing engagement with said grinding wheel and for rotation thereby when said mechanism is in said operative position, means operatively connected to said mechanism actuable to move said mechanism from said inoperative to said operative position, a cam carried by said mechanism, a follower engaged by said cam when said mechanism approaches said operative position, and operative connections from said cam to said crushing wheels effective through the action of said cam on said follower to move said crushing wheels toward the axis of said grinding wheel as said mechanism is moved fully to said operative position.

8. In a grinding machine having a bed, a rotary grinding wheel carried by said bed and means for rotating said wheel, a crush dressing mechanism comprising a frame pivotally mounted on said bed for swinging between an inoperative and an operative position, said frame being slidable transversely of said pivot and having a pair of freely rotatable crushing wheels supported for crushing engagement with said grinding wheel and for rotation thereby when said mechanism is in said operative position, one of said crushing wheels being journaled on said frame and the other of said crushing wheels mounted for movement on said frame toward and from said one crushing wheel, means operatively connected to said mechanism actuable to move said mechanism from said inoperative to said operative position, a cam carried by said frame, a follower carried by said bed and with which said cam engages when said mechanism approaches said operative position for moving said frame in a direction to move one of said crushing wheels toward the axis of said grinding wheel, and connections from said frame to the other of said crushing wheels causing the cammed motion of said frame to move the other of said crushing wheels toward said grinding wheel axis.

9. Ina grinding machine having a bed, a carriage mounted for linear motion on said bed, a rotary grinding wheel journaled in said carriage on an axis transverse to its direction of motion on said bed, means for rotating said wheel, a crush'dressing mechanism pivotally mounted on said bed for swinging between an inoperative and an operative position and having a pair of freely rotatable crushing wheels supported for crushing engagement with said grinding wheel and for rotation thereby when said mechanism is in said operative position, means interconnecting said crushing wheels for equal and opposite movement from and toward each other with reference to the pivotal mounting of said mechanism, means operatively connected to said mechanism actuable to move said mechanism from said inoperative to said operative position, a cam carried by said mechanism, a lever pivoted to said bed about an axis transverse to the direction of motion of said carriage, a link connecting one end of said lever to said carriage, a follower carried by the opposite end of said lever and with which said operative cam engagm when said mechanism approaches said position for moving said cam, and operative connections between said cam and crushing wheels causing the motion of said cam by engagement on said follower to move said crushing wheels toward each other and into engagement with said grinding wheel.

10. In a grinding machine having a rotary grinding wheel and means for rotating said wheel, a base, a slide mounted on said base for motion toward and from said grinding wheel, crush dressing mechanism pivoted on said slideand swingable about said pivot between a position for dressing said wheel and an inoperative position, a cam carried by said mechanism, a lever fulcrumed on said base and having a follower cooperating with said cam, said dressing mechanism comprising a pair of spaced freely rotatable crushing rolls, one of said rolls being mounted for motion in the direction of said slide on said base when said mechanism is inthe dressing position, said cam and follower being arranged to move said one roll toward said grinding wheel when said mechanism is being swung to wheel dressing position, and an operative connection between said lever and slide causing motion of said slide to move the other of said rolls toward said grinding wheel in the opposite direction to the motion of said one roll as said one roll is so moved on the swinging of said mechanism toward wheel crushing position.

References Cited in the file of this patent UNITED STATES PATENTS Great Britain Feb. 2, 1942 

